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Microparticle suspensions are prevalent in both natural and industrial environments, playing a crucial role in various processes. The heat transfer characteristics between particles and fluids are critical to many of these processes. This study employs the Arbitrary Lagrangian-Eulerian finite element method to simulate and analyze the particle dynamics and fluid–solid heat transfer characteristics within a microchannel, aiming to determine fluid–solid heat transfer characteristics based on the average temperature of particles. The effects of five factors (particle thermal conductivity, specific heat capacity, fluid Reynolds number, particle diameter, and initial particle position) were comparatively analyzed. The results indicate that particles in a laminar microchannel reach a self-equilibrium position under the combined action of fluid shear gradient and wall lift force, with particle size being the primary influencing factor. The shear effect of the fluid causes the particle to rotate, thereby enhancing the convective heat transfer between the particle and the fluid. The Reynolds number also significantly impacts this process. Additionally, thermal conductivity, specific heat, particle size, and position can influence the fluid–solid heat transfer characteristics by altering the internal temperature distribution of the particle. We derived an expression for the Nusselt number using a dimensionless analysis method, which describes the heat transfer between the particle and fluid based on the average temperature of the microparticle.

In the present study, the effect of the alternative magnetic field (AMF) on the metal pool shape, primary carbides formation, and mechanical properties during vacuum arc remelting (VAR) process was investigated by experiments and numerical simulations. Without AMF, the original depth of the molten pool was 87.74 mm. The application of the AMF decreased the depth of the metal pool, to various degrees (86.46 mm at 40 Gs 0.5 Hz, 78.96 mm at 40 Gs 0.1 Hz, 69.82 mm at 40 Gs 0.05 Hz). As a consequence, the primary carbides became more refined average size reduced by 20.66%∼25.72%. After modification, uniformly distributed hardness and improved wear resistance was achieved. Meanwhile, compared with 0.5 and 0.1 Hz cases, the strengthening effect was more obvious at 0.05 Hz. The numerical simulation results showed that, the AMF and the melting current in the molten steel produced Lorentz force, which caused the horizontal circulation. Therefore, the temperature of metal pool became more homogenized under the horizontal circulation. When the frequency was 0.05 Hz, the horizontal circulation in liquid steel was more intense, which makes the temperature field more uniform. Horizontal circulation can also reduce the segregation of alloying elements, which restrains the precipitation condition and refines primary carbides. The hardness uniformity can also be attributed to the uniform distribution of alloying elements. The improvement in wear resistance is attributed to the refinement of the primary carbide, thereby reducing the occurrence of primary carbide spalling during friction.

Sulfilimines, the aza analogues of sulfoxides, are of increasing interest in medicinal and agrochemical research programs. However, the development of efficient routes for their synthesis has remained relatively unexplored. In this study, we report a transition metal-free, selective S-arylation reaction between sulfenamides and arynes, enabling the facile preparation of structurally diverse sulfilimines under mild and redox-neutral conditions in good yields. The application value of our method was further demonstrated by scale-up synthesis, downstream derivatization, and robustness screen.

The current work investigated the impact of transverse static magnetic field (TSMF) with varied magnetic flux density (MFD) on cleanliness and microstructure of laboratory scale electroslag remelted H13 die steel. The inclusion morphology and microstructure evolution of electroslag remelted ingots were examined utilizing scanning electron and optical microscopes, respectively. The number and size of inclusions in ingots were detected using the FEI Aspex Explorer. The results demonstrated that the number/size of inclusions in H13 electroslag remelted ingots were decreased as the MFD of applied TSMF increased. This resulted from the application of the TSMF, which produced the thinner liquid melting film (LMF), smaller droplets, and shallower metal molten pool, strengthening the kinetic conditions for inclusion migration to the slag-metal interface and the removal process. When the MFD of the applied TSMF was higher (95 mT and 140 mT), the LMF became thinner, the droplets became smaller, and the metal pool became shallower were more visible. Moreover, the metal pool became shallower and the local solidification time became shorter after applying TSMF with larger MFD, resulting in finer dendritic structure and carbides.

The long acquisition time has limited the accessibility of magnetic resonance imaging (MRI) because it leads to patient discomfort and motion artifacts. Although several MRI techniques have been proposed to reduce the acquisition time, compressed sensing in magnetic resonance imaging (CS-MRI) enables fast acquisition without compromising SNR and resolution. However, existing CS-MRI methods suffer from the challenge of aliasing artifacts. This challenge results in the noise-like textures and missing the fine details, thus leading to unsatisfactory reconstruction performance. To tackle this challenge, we propose a hierarchical perception adversarial learning framework (HP-ALF). HP-ALF can perceive the image information in the hierarchical mechanism: image-level perception and patch-level perception. The former can reduce the visual perception difference in the entire image, and thus achieve aliasing artifact removal. The latter can reduce this difference in the regions of the image, and thus recover fine details. Specifically, HP-ALF achieves the hierarchical mechanism by utilizing multilevel perspective discrimination. This discrimination can provide the information from two perspectives (overall and regional) for adversarial learning. It also utilizes a global and local coherent discriminator to provide structure information to the generator during training. In addition, HP-ALF contains a context-aware learning block to effectively exploit the slice information between individual images for better reconstruction performance. The experiments validated on three datasets demonstrate the effectiveness of HP-ALF and its superiority to the comparative methods.

This investigation determined the creep-fatigue cyclic-life (Nf) saturation effect for the DZ445 superalloy with 16–128 min dwell time at 900 °C and total strain range of 1.6%. When the dwell time exceeds 8 min, the mechanical response including maximum stress response, hysteresis loop, plastic strain range, and stress relaxation amount at characteristic cycle are also saturated with dwell time gradually. The Nfsaturation effect is also reflected in the creep- and ductile-dominated fracture modes. This critical phenomenon is closely related to the dynamic equilibrium reached between the superdislocations of a/2[101] in γˊ precipitation and the formation of the dislocation networks. While the rupture time is increased continuously with dwell time, which could be better used as an evaluation index when the cyclic life is saturated. The Nfsaturation effect can not only reduce the cost of tests with long-dwell time, but also provide the guidance for creep-fatigue safety design.

The effect of an axial static magnetic field (ASMF) on the carbides and mechanical properties of electroslag remelted H13 die steel was studied in current work. Optical microscope (OM) and scanning electron microscope (SEM) were used to analyze the solidification structure and carbide morphology of electroslag remelting (ESR) ingots. The FEI Aspex Explorer was utilized to detect the inclusions in H13 ESR ingots. Compared with conventional ESR, the application of ASMF in this study made the metal molten pool shallower and flatter, resulting in shorter local solidification time and uniform distribution of solute atoms, which alleviated the element segregation degree, and further inhibited the formation of primary carbides. The magnetic-controlled electroslag remelting (MC-ESR) process not only refined the dendrite structure (tended to grow parallel to the ingot axis) and the carbides, but also improved the inclusion removal efficiency and mechanical properties of H13 ESR ingots.

• A high performance Cu-1Cr-0.1Zr alloy was obtained by continuous extrusion forming and subsequent aging treatment. • The strengthening contributions of the grain refinement, dislocation and precipitation were quantitatively calculated. • The wear behavior was studied by examining the evolution of wear surface morphology and subsurface microstructure. • The microhardness (H), H/E r ratio and H3/E r 2 ratio were considered to gage the wear resistance of Cu-Cr-Zr alloy. As a promising material for the new generation of high-speed railway contact wires, the comprehensive optimization of the electrical conductivity, strength, hardness and wear resistance of the Cu-Cr-Zr alloy has received extensive attention. In this paper, a high-performance Cu-1Cr-0.1Zr alloy with an ultimate tensile strength of 599.1 MPa, a uniform elongation of 8.6%, a microhardness of 195.7 HV 0.2 and an electrical conductivity of 80.07%IACS was achieved by the continuous extrusion forming (CEF) and subsequent peak-aging treatment. The grain refinement strengthening, dislocation strengthening and precipitation strengthening are identified to be responsible for the excellent electrical and mechanical properties of Cu-Cr-Zr alloy. The wear behavior of Cu-Cr-Zr alloy was investigated by examining the evolution of worn surface morphology and subsurface microstructure. The microhardness (H) and reduced elastic modulus (E r) of the subsurface below the worn surface measured by nanoindentation were calculated to gage the tribological performance of Cu-Cr-Zr alloy. Results show that the continuously extruded and subsequently peak-aged specimen has the best wear resistance, which indicates that the tribological properties of Cu-Cr-Zr alloy strongly depend on its strength and hardness. It can be concluded that the CEF and subsequent aging treatment process provides a new and high-efficiency procedure for the continuous preparation of Cu-Cr-Zr alloys. [ABSTRACT FROM AUTHOR]

• Detailed 3D microtomography characterizations of inclusions in electrode tip are performed. • Motion/removal behavior of inclusions in electrode tip are clarified based on experimental results and simulation verification. • The number and size of the inclusions in LMF are decreased due to the applied ASMF. • The mechanism is that the ASMF enhances the kinetic conditions for inclusion migrating to LSI and removal in LMF. Detailed three-dimensional (3D) microtomography characterizations of inclusions in electrode matrix, mushy zone (MZ) and liquid melt film (LMF) were performed to elucidate the motion and removal behavior of inclusions in electrode tip during magnetically controlled electroslag remelting (MC-ESR) process. A transient 2D numerical model was also built to verify the experimental results and proposed mechanisms. The number and size of inclusions exhibited an obvious increasing trend from edge to mid region in LMF, while remained almost the same in electrode matrix and MZ. The inclusions in LMF migrated from edge to mid region of LMF, accompanied with removal process. In addition, the kinetic conditions for inclusion migrating to LMF/slag interface (LSI) were enhanced during MC-ESR process, thereby improving the inclusion removal efficiency in LMF. This work highlights the 3D characterization and motion/removal mechanisms of inclusions in electrode tip, as well as sheds new light on preparing high purity materials. [Display omitted] [ABSTRACT FROM AUTHOR]

A transverse static magnetic field (TSMF) was superimposed during electroslag remelting (ESR) process to regulate the shape of metal pool, the eutectic carbides morphology as well as the mechanical properties of electroslag remelted M2 high-speed steel (HSS) in current study. The metal pool became shallower and flatter after applying a 65 mT TSMF. Moreover, refined eutectic carbides and solidification structure (tended to grow axial) of the ESR ingot were obtained, together with uniform/improved mechanical properties (hardness, wear). Modifications of the morphology of metal pool and grain growth angle under the TSMF were attributed to a periodic electromagnetic excitation effect on droplets transition characteristics, which changed the drop path of the droplets (single to multiple drop) and homogenized the temperature distribution in metal pool. In addition, local solidification time (LST) became shorter and the number of inclusions ((Ti, V)N–Al2O3and (Ti, V)N) which acted as heterogeneous nuclei for eutectic carbides formation increased (the inclusions also became finer) due to TSMF, resulting in the refinement of the eutectic carbides in ESR ingots.

[Display omitted] • Developing a bulk cast Al 19.25 Co 18.86 Fe 18.36 Ni 43.53 EHEA with lamellar eutectics. • The developed as-cast EHEA featuring an extraordinary strain-hardening capability. • Uncovering the deformation and fracture mechanisms at multiple length scales. • A few slip lines and lattice dislocations appearing in the hard B2 lamellae. • But dynamic microstructure refinement is identified in the ductile L1 2 lamellae. Over recent years, eutectic high-entropy alloys (EHEAs) have intrigued substantial research enthusiasms due to their good castability as well as balanced strength–ductility synergy. In this study, a bulk cast Al 19.25 Co 18.86 Fe 18.36 Ni 43.53 EHEA is developed with fine in-situ lamellar eutectics. The eutectics comprise alternating ordered face-centered-cubic (L1 2) and ordered body-centered-cubic (B2) phases with semi-coherent interfaces. The resulting microstructure resembles that of most reported as-cast EHEAs, but the B2 lamellae are devoid of nano-precipitates because of the Cr-element removal in current tailored eutectic composition. Surprisingly, the B2 lamellae still feature much higher deformation resistance than the L1 2 lamellae, so that less lattice defects are detected in the B2 lamellae until the fracture. More interestingly, in the L1 2 lamellae we identify a dynamic microstructure refinement that correlates to extraordinary strain hardening in tension. The precipitate-free EHEA consequently shows excellent tensile ductility of ∼10 % and high ultimate strength up to ∼956 MPa. [ABSTRACT FROM AUTHOR]

ABSTRACTThe morphology of eutectic carbide was studied by application of a transverse static magnetic field (TSMF) during the directional solidification of M2 high-speed steel. The results show that the morphology of eutectic carbide changed from lamella to fibre as the magnetic flux density (MFD) increased from 0 to 1 T. The transformation from lamella to fibre has been enhanced by the increasing MFD. Solute elements moved and gathered at a certain region in the mushy zone when imposing a TSMF. In the mushy zones, channel segregations were formed in the samples treated by 0.2 and 0.4 T TSMF. When the MFD increased to 0.8 and 1 T, the channel segregation disappeared. Morphology transition, solute elements movement and formation of channel segregation were attributed to the thermoelectric magnetic force (TEMF). This work provides a new method to control the distribution of carbides in steel assisted by TEMF.

The morphology of eutectic carbide was studied by application of a transverse static magnetic field (TSMF) during the directional solidification of M2 high-speed steel. The results show that the morphology of eutectic carbide changed from lamella to fibre as the magnetic flux density (MFD) increased from 0 to 1 T. The transformation from lamella to fibre has been enhanced by the increasing MFD. Solute elements moved and gathered at a certain region in the mushy zone when imposing a TSMF. In the mushy zones, channel segregations were formed in the samples treated by 0.2 and 0.4 T TSMF. When the MFD increased to 0.8 and 1 T, the channel segregation disappeared. Morphology transition, solute elements movement and formation of channel segregation were attributed to the thermoelectric magnetic force (TEMF). This work provides a new method to control the distribution of carbides in steel assisted by TEMF.

A new, to the best of our knowledge, scheme for the generation of ultra-flat optical frequency combs (OFCs) is proposed, which mainly uses a polarization modulator (PolM) and a first-order Butterworth band-stop filter. The PolM is driven by a digital periodic square-wave signal, and the output of the PolM is an uneven OFC. The function of the Butterworth band-stop filter is to obtain flat and stable OFCs by changing its bandwidth. The comb spacing of the OFCs can be adjusted by changing the period of the square-wave signal. The theoretical model for the scheme is also established. The simulation results show that the generator constructed according to the proposed scheme can produce 64, 128, and 256 comb lines with 200 MHz comb spacing and with spectral flatness lower than 0.3 dB. The comb spacing can be further increased by using the square-wave signal at GHz rates, and the generated OFCs exhibit good frequency tunability.

To generate a flat optical frequency comb (OFC), a new scheme based on a dual-parallel Mach–Zehnder modulator and a single recirculation frequency shift loop is proposed and analyzed. Compared with the traditional single loop recirculation frequency shift method, the quantity of comb lines is doubled, and the comb flatness is better when the number of cycles is the same. The theoretical analysis model is established, and the simulation results show that a 111-line OFC with frequency spacing of 10 GHz, flatness of 1.32 dB, and optical signal to noise ratio of 27.4 dB can be obtained by adopting the proposed scheme.

Semi-solid forging of iron-based alloys during solidification has unique characteristics distinct from those of the classical hot forging. With the aim of acquiring precise knowledge concerning the microstructural evolution of bearing steel Cr4Mo4V in this process, a series of semi-solid forging experiments were carried out in which samples were wrapped in a designed pure iron sheath. The effects of forging temperature and forging reduction on the grain morphology and liquid flow behavior were investigated, respectively. By forging solidifying metal (FSM), bulky primary dendrites were broken and spheroidal grains with an average shape factor of 0.87 were obtained at 1360 °C. With the decreasing forging temperature to 1340 °C, the microstructural homogeneity can be improved. On the other hand, it shows that a higher forging reduction (50%) is essential for the spheroidization of grains and elimination of liquid segregation. Those microstructural characteristics are related to different motion mechanisms of solid and liquid phases at different forging temperatures. Additionally, the effect of semi-solid forging on the eutectic carbides was also investigated, and the results demonstrate that the higher diffusion capacity and less liquid segregation jointly lower the large eutectic carbides and consequently cause its uniform distribution during FSM. [ABSTRACT FROM AUTHOR]

Screening plants that are hypertolerant to and excluders of certain heavy metals plays a fundamental role in a remediation strategy for metalliferous mine tailings. A field survey of terrestrial higher plants growing on Mn mine tailings at Huayuan, Hunan Province, China was conducted to identify candidate species for application in phytostabilization of the tailings in this region. In total, 51 species belonging to 21 families were recorded and the 12 dominant plants were investigated for their potential in phytostabilization of heavy metals. Eight plant species, Alternanthera philoxeroides, Artemisia princeps, Bidens frondosa, Bidens pilosa, Cynodon dactylon, Digitaria sanguinalis, Erigeron canadensis, and Setaria plicataaccumulated much lower concentrations of heavy metals in shoots and roots than the associated soils and bioconcentration factors (BFs) for Cd, Mn, Pb and Zn were all < 1, demonstrating a high tolerance to heavy metals and poor metals translocation ability. The field investigation also found that these species grew fast, accumulated biomass rapidly and developed a vegetation cover in a relatively short time. Therefore, they are good candidates for phytostabilization purposes and could be used as pioneer species in phytoremediation of Mn mine tailings in this region of South China.

The anti-human bladder cancer monoclonal antibody BDI-1 was radio-labeled with rhenium-188 by direct labeling methods using SnCl2 as reductant and MDP as stannous stabilizer or by indirect method using NHS-ECM ester as bifunctional chelator. Radiochemical yields of 30±7.23% and 87.4±5.67% and radiochemical purity of more than 95% were achieved. The inmmunoreactive fraction was 58.7%. The results showed that radionuclide ¹⁸⁸Re might be employed using the same labeling methodology with ^99mTc labeling of BDI-1 for radiommunoimaging (RII) and radioimmunotherapy (RIT) and that may be useful in radioimmunodetection and RIT of human bladder carcinoma in vivo. Copyright © 2001 John Wiley & Sons, Ltd.

A multiresolution time-domain (MRTD) method based on Daubechies scaling functions is proposed for the time-domain analysis of planar optical waveguide devices. The anisotropic perfectly matched layer absorbing boundary condition is implemented for the MRTD method. The proposed scheme is used to model the parallel-slab directional coupler, and the simulation results are in good accord with the analytical solutions. Compared with the standard finite-difference time-domain method, this scheme can save considerably computer resources without loss of accuracy. © 2005 Society of Photo-Optical Instrumentation Engineers.